, Volume 471, Issue 2, pp 430-438
Date: 28 Aug 2012

The Withdrawn ASR™ THA and Hip Resurfacing Systems: How Have Our Patients Fared Over 1 to 6 Years?

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Topic
Hip

Abstract

Background

The Articular Surface Replacement™ (ASR™) metal-on-metal hip arthroplasty system (DePuy Orthopaedics, Inc, Warsaw, IN, USA) reportedly has a higher than anticipated early failure rate leading to a voluntary recall. This prompted us to evaluate all ASR™ components implanted at our center.

Questions/Purposes

In all ASR™ components, we reported (1) revision rate, (2) blood metal ion levels, and (3) intraoperative findings for revisions related to adverse reaction to metal debris (ARMD).

Methods

We retrospectively reviewed all 172 patients (190 hips) who underwent THA (149 hips) or hip resurfacing (41 hips) with the ASR™ system. We determined failure rates. We obtained blood metal ion concentrations from 93 patients at last followup. We evaluated MRI studies and intraoperative histopathology. Minimum followup was 12 months (mean, 40 months; range, 12–74 months).

Results

At latest followup, we had revised 24 of 190 hips (13%): in 18 patients with THA and five patients with resurfacing. Mean time to revision was 45 months (range, 12–75 months). Mean blood concentrations were 13 μg/L (range, 0–150 μg/L) for cobalt and 6 μg/L (range, 0–87 μg/L) for chromium. Mean prerevision blood metal ion levels were higher in the revised group (cobalt: 48 μg/L; chromium: 18 μg/L) than in the nonrevised group (cobalt: 5 μg/L; chromium: 2 μg/L). ARMD was present in 14 of the 24 hips revised in this study.

Conclusions

Surgeons must have a low threshold for concern for ARMD in patients with ASR™ systems. Blood metal ion levels and MRI can be used to evaluate patients with underperforming implants. Intraoperative histopathologic analysis and joint fluid cytology can help diagnose ARMD at the time of revision.

Level of Evidence

Level III, therapeutic study. See Instructions for Authors for a complete description of levels of evidence.

One of the authors (TPV) certifies that he, or a member of his immediate family, has received or may receive payments or benefits, during the study period, an amount of more than $100,000 from DePuy Orthopaedics, Inc, a Johnson and Johnson company, Warsaw, IN, USA. One of the authors (KTH) certifies that he has received a stipend, during the study period, from Duke University’s CTSA Grant TL1RR024126 from NCCR/NIH. Each remaining author certifies that he or she, or a member of his or her immediate family, has no commercial associations (eg, consultancies, stock ownership, equity interest, patent/licensing arrangements, etc) that might pose a conflict of interest in connection with the submitted article.
All ICMJE Conflict of Interest Forms for authors and Clinical Orthopaedics and Related Research editors and board members are on file with the publication and can be viewed on request.
Clinical Orthopaedics and Related Research neither advocates nor endorses the use of any treatment, drug, or device. Readers are encouraged to always seek additional information, including FDA approval status, of any drug or device before clinical use.
Each author certifies that his or her institution has approved the human protocol for this investigation and that all investigations were conducted in conformity with ethical principles of research.
This work was performed at Duke University Medical Center, Durham, NC, USA.